Growers look to sunscreen to help protect vines from heat-stress

Research trials, funded through the GWRDC Regional Program, will use results from this vintage to evaluate new and existing sunscreen products, providing growers with the latest advice on how to best protect vines against sunburn and heat-stress.

The GWRDC Regional Program is designed to encourage regional adoption and adaption of research findings and is offered to all grape-growing regions.  The Greater-NSW Regional Program covers 15  GIs across NSW and Canberra (excluding the Riverina) and is managed by the NSW Wine Industry Association and NSW Department of Primary Industries Development Officer Jason Cappello.

The Greater-NSW trials are multi-pronged studies into the use of sunscreen products in vineyards. Based in the Hunter, they aim to increase grower awareness about the potential role sunscreen products can play in maintaining or improving fruit quality and the effects on the timing of harvest.

Now in their second year, the trials are being run by viticulture consultant Liz Riley and compare two products, ‘Surround’ and ‘Screen Duo’ against a control. The trials include wine quality assessments from each site.

Ms Riley said the activity was also designed to assess the costs associated with these products and their application; the trials look at application late season or prior to a heatwave in an attempt to identify ‘the balance between the investment in product and spray application versus benefit’.

The Hunter trials will also feed into other sunscreen trials taking place across Australia, including the Riverina.

The Riverina project, which is being undertaken by Mr Cappello, will look at the best-practice use and application of the most commonly used kaolin clay (sunscreen) spray products, as well as a new product used predominantly on stonefruit ‘Photon’.

‘Photon 500SG’ was only released for commercial horticulture use two years ago and differs from kaolin sunscreen products in that it’s a a translocated product which is absorbed by the plant within 5–6 hours, leaving no residue on the surface of the fruit or leaves.

Mr Cappello detailed other benefits including the recommended application rate of 20grams per hectare; significantly less than other more common kaolin clay products (some as high as 50 kilograms/ha).

‘Greater-NSW and the Riverina are some of Australia’s hottest grapegrowing regions, so heat-stress management is the main driver for this project, but with an additional look at cost-effectiveness’, he said.

‘We plan to trial the sunscreen using the recommended methods, applying at regular intervals across the vintage period and also on an ad hoc basis – for example just prior to a heatwave.

‘We want to record and compare the results – to make sure growers are using these products in the best and most cost-effective way possible’.

The trial will also collect data on the possible effect of sunscreen on grape colour and canopy temperatures.

‘It’s routine to collect this sort of data throughout harvest, but in this case we will hopefully be able to feed into some of the additional sunscreen/colour trials happening in the Riverina’, he said.